We need more information, sadly. What exactly are you feeding them? Examples: amprolium medicated chick starter grower
What is the exact temp of the brooder?
What heat source are you using?
When the babies are sleeping, do they pile on one another? Do they all sit under the light, or do they sit away from it on the edges, or spread about around the brooder?
Are you using anything in the water?
You will indeed need a coccidiocide actually - the coccidiostat is the med in the feed. Sulmet or Corid are two common and good choices. I'd also pick up a B-complex vitamin from the store, and Enfamil PolyViSol baby vitamins (non-iron) from the vitamin section of
Walmart, etc. And either plain unflavored yogurt, or acidophilis capsules from the vitamin section.
Any chance that the babies got any water in their food and it soured? Or any spilled in their bedding?
Is the feed you're using very very fresh, stored cool and dark, smells strongly of fresh ingredients?
Do you keep them on shavings, paper, newspaper, hay, or wire?
Do you clean out their waterers twice a day if you see droppigns in the waterer?
I'd hold off on the egg yolk (and if you ever feed it, feed it cooked - boiled) because sometimes cocci (in coccidiosis) bloom with added protein. But I'd get some ready just in case.
p.s. Definitely I'd buy a different bag of feed in case something's wrong with the feed. Pick up a poultry vitamin/electrolyte package while you're there getting the Sulmet or Corid. Chick starter, amprolium as the only medication, and make sure it's good and fresh before you leave the feed store parking lot by smelling it. If it smells like cardboard, it's not fresh.
